Abstract: This report describes the current state of work
with PMON, a logic for reasoning about action and change. PMON has been
assessed correct for the K-IA class using Sandewall's Features and Fluents
framework which provides tools for assessing the correctness of logics of
action and change. A syntactic characterization of PMON is provided in terms
of a circumscription axiom which is shown to be reducible to a first-order
formula. This creates the possibility for efficient implementation of the
logic, a topic discussed in this report. In addition, besides considering the
frame problem, PMON is extended to PMONR in order to deal with some
restricted types of the ramification problem. It is also shown that PMONR is
reducible to the first-order case. A number of benchmark examples are
analyzed which show the advantages of reduction to the monotonic first-order
case. In addition, an appendix is provided with a detailed description of the
surface language for action scenarios and its reduction to the base logic FL,
a first-order sorted logic.